Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2001-02-12
2004-05-11
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C428S098000
Reexamination Certificate
active
06734273
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to thermoplastic polyurethanes and films and numerous articles which can be made therefrom. More particularly, the invention relates to linear thermoplastic polyurethanes having high molecular weight that are made from polyols having high secondary hydroxyl content. The thermoplastic polyurethanes of the present invention have excellent physical properties and can be made by a one-shot continuous polymerization method such as in an extruder.
BACKGROUND OF THE INVENTION
Heretofore, thermoplastic polyurethane polymers were typically formulated with polyols having predominantly primary hydroxyl groups.
Canadian Application No. 2,233,664 to Scholz relates to a process for preparing thermoplastic polyurethanes by reacting (a) isocyanates with (b) compounds reactive toward isocyanates and having a molecular weight of from 500 to 10,000 g/mol. in the presence or absence of (c) chain extenders having a molecular weight of less than 500 g/mol. (d) catalysts and/or (c) customary auxiliaries and additives, the component (b) used comprises at least one polyether polyalcohol (bl) comprising polyoxypropylene and polyoxyethylene units and having a molecular weight of from 500 to 10,000 g/mol, an unsaturation of less than 0.07 meq/g and a primary hydroxyl group content of from 80 to 100%. U.S. Pat. No. 4,202,957 to Bonk et al. relates to polyurethane polyether-based elastomers which are thermoplastic, recyclable and have increased high temperature resistance which permits fabrication by injection molding. The elastomers are the product of reaction of 4,4′methylenebis(phenyl isocyanate), a particular group of polypropylene oxide-polyethylene oxide block copolymers and an extender [straight chain aliphatic diols C
2-6
or the bis(2-hydroxyethyl ether) of hydroquinone or resorcinol]. The block copolymers have at least 50 percent primary hydroxyl groups, a pH in the range of 4.5 to 9, a content of alkali metal ion less than 25 ppm and a molecular weight of 1000 to 3000. In a particularly preferred embodiment the elastomers are prepared by replacing up to 25 percent by equivalents of the extender by certain diols (polyethylene glycols up to 1500 M.W. preferred). The polyether diols are polyoxypropylene polyoxyethylene, block copolymeric glycols which are obtained by first polymerizing propylene oxide and then reacting the resulting polyoxypropylene glycol with ethylene oxide in a multi-step process, see column 3, lines 14-20. The multi-step process for performing the polyether diols is performed using a basic catalyst, see column 3, lines 21-33.
Thermoplastic polyurethanes formulated with polyols having high primary hydroxyl group content are more costly than the compositions of the present invention which utilize polyols having a substantial amount of secondary hydroxyl groups.
Although mixtures of primary and secondary hydroxyl group containing polyols are not new, previously they have primarily only been used in thermoset polyurethanes such as in coatings, sealants and foams; where high molecular weights and useful properties can only be achieved by chemical cross-linking.
Antipodally, the polyurethanes of the present invention are not thermosets, but instead are thermoplastics which are substantially linear and free of cross-links.
SUMMARY OF THE INVENTION
The thermoplastic polyurethanes of the present invention are prepared from reactants comprising polyether polyols having high secondary hydroxyl content, at least one polyisocyanate, at least one chain extender and optionally, at least one catalyst. The polyurethane compositions are substantially linear, substantially non-thermoset and hence substantially free of cross-links, and have high molecular weights which display excellent mechanical properties comparable to high primary hydroxyl containing polytetramethylene ether glycol (PTMEG) polyols which are relatively more expensive to produce and utilize than the polyols of the present invention.
Polyurethanes as described herein can be prepared by a one-shot polymerization process, wherein all of the reactants are brought simultaneously or substantially simultaneously and reacted. The one-shot process is preferably performed in an extruder.
The thermoplastic polyurethanes can be formed into tubings, cable jacketing, and breathable films for such uses as roofing membranes and house wrap applications. It has been found that the films prepared by the invention have excellent water vapor transmissibility.
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic polyurethane polymers of the present invention, comprise the reaction product of polyether-based polyols, polyisocyanates, preferably diisocyanates, chain extenders, and optionally, catalyst.
Polyols
The present invention advantageously utilizes a polyol component including polyether polyols of high secondary/low primary hydroxyl group content which are produced in a single step process, wherein all of the monomers are reacted at simultaneously or substantially the same time using double metal cyanide catalysts. Polyether polyols produced by this method are randomly polymerized and possess low unsaturation with functionality approaching two, making them suitable for the manufacture of high molecular weight, linear thermoplastic polyurethanes. Since no base neutralization and catalyst purification/removal are necessary, such as with the conventional base catalyzed urethane polyether polyols, the manufacturing process of the high secondary/low primary hydroxyl content polyethers polyols is cost competitive. The high secondary content polyether polyols importantly are substantially free of monofunctional impurities, which is a requirement for making high molecular weight linear thermoplastic urethanes.
Several different classes of polyols can be used in the polyol component of the polyurethanes of the present invention. At least a portion of the total polyol component of the present invention is prepared from polyalkylene oxides which result in polyether polyols having high secondary hydroxyl group (—OH) content or low primary hydroxyl group content. An important feature of the present invention is that the polyether polyol contains generally about 20, 30 or 35 to about 95 or 100 percent, desirably from about 40, 51, 53, or 65 to about 80 85, or 90 and preferably from about 50, 51 or 52 to about 55, 60, 65, 80, or 85 percent of secondary hydroxyl groups based on the total number of hydroxyl groups in the high secondary hydroxyl content polyether polyols.
The polyether polyols of the present invention having high secondary hydroxyl content are prepared from one or more alkylene oxides having from 2 to about 6 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide, and the like. Desirably, the polyether polyol is often a polypropylene oxide copolymer with at least one additional alkylene oxide such as ethylene ioxide, the amount of propylene oxide desirably being at least about 60 percent by weight and preferably at least about 75 percent to about 100 percent by weight of the copolymer. While butylene oxide can be utilized, the same is generally not preferred due to its high cost and poor vapor transmissibility properties. The polyether polyols can be produced by reacting a glycol, such as propylene glycol with propylene oxide, and ethylene oxide.
The high secondary hydroxyl content polyether polyols are commercially available from the Olin Corporation of Cheshire, Conn. as Poly-L, the Bayer AG of Leverkusen, Germany, as Arcol R-2835. The high secondary hydroxyl content polyols are generally prepared in the presence of various catalysts and desirably a double-metal cyanide catalyst. The use of double-metal cyanide catalyst, such as zinc hexacyanometallate made by Arch Chemical, and the preparation of high molecular weight polyols therewith is known to the art. For example, U.S. Pat. No. 3,829,505 assigned to the General Tire & Rubber Company, discloses the preparation of high molecular weight diols, triols, etc., using double-metal cyanide catalysts. The number
Dunlap Thoburn T.
Gorr Rachel
Hudak Daniel J.
Noveon IP Holdings Corp.
Powell Joe A.
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